This invention falls within the field of art of baseband data processing of radio-frequency signals and, in particular, relates to the adaptive filtering of narrow band interference, either intentional or unintentional. It is applicable to spread spectrum communicators, radar, navigation and identification equipments.
In the past, narrow band interference filtering has been accomplished by using RF tunable notched filters. Such filters are usually large and expensive to produce and are not generally suitable for high volume production. Also, it is difficult to build narrow band RF filters since the size of the filter is inversely related to bandwidth. This means that very narrow band RF tunable notched filters require very large components. These disadvantages are overcome by utilizing the baseband data processing and adaptive filter approach of the present invention. It is a general advantage that baseband circuits can be built using solid state monolithic circuits which result in lower cost and smaller size for high volume production. There are also functional advantages in that the bandwidth and center frequency of such filters can be easily adjusted and the bandwidths can be made arbitrarily narrow.